Opioid Overdose Deaths Fell After Colorado Legalized Weed

It could be just a coincidence, but more research is definitely needed.

Medical marijuana is already associated with fewer people killed by opioids like prescription painkillers and heroin. One study found that states with legalized medical weed had a 25 percent lower rate of opioid overdoses than states without MMJ, perhaps because marijuana can treat the same chronic pain often afflicting opioid users. That's made experts wonder whether full marijuana legalization could have a similar (or even greater) effect. Now, one of the first studies to take up that question suggests the early answer is yes.

Researchers from the University of North Texas Health Science Center, the University of Florida, and Emory University charted opioid-related deaths in Colorado from the beginning of 2000 to the end of 2015; they looked at deaths involving both pharmaceutical and nonpharmaceutical drugs. The result showed a disturbing upward trend—until 2014, when deaths began to decrease. Starting in January 2014, people in Colorado could legally buy marijuana for recreational use. After that point, the study found, opioid-related deaths declined by 6.5 percent. That works out to nearly one fewer person per month dying of an overdose.

Those numbers should come with some caveats, though. First, it's based on only two years of data, 2014 and 2015. That's not much time to work with, and the authors themselves stress that this is preliminary work that deserves more follow-up.

Second, it can be difficult to untangle the potential effects of legal pot from other effects. For example, in 2014 Colorado legalized weed—but also stepped up its monitoring of prescription drugs, which was intended to cut down on opioid addiction. The authors acknowledge that part of the decrease may be attributable to better control of prescriptions and they did try to control for that factor, but, again, further study will be needed.

Around the same time in Colorado, public education about the dangers of opioids was increasing. A consortium of doctors, pharmacists, policy officials, and others dedicated to reducing prescription drug abuse had begun to work. And naloxone, used in emergencies to reverse overdoses, had become more widely distributed, probably saving lives.

All of these are potentially complicating factors, according to Robert Valuck, who coordinates the Colorado Consortium for Prescription Drug Abuse Prevention. He's skeptical that the study can conclusively say legal pot is helping beat back the opioid epidemic. "The whole thing is so convoluted, with so many different things going on in the marketplace, it's virtually impossible to assign cause and effect or credit and blame to any one thing," he told the Denver Post.

He also notes that while opioid deaths overall have declined in the state in 2016, heroin deaths are on the rise, according to preliminary numbers from the Colorado health department. It's common for users to switch from opioid painkillers to heroin, and that move may be reflected in the overdose numbers.

Again, the study authors acknowledge this is preliminary research—officials should follow the data to see if the trend continues and the link should be examined in other states that have legalized recreational marijuana, like Oregon and Washington. But given that opioids kill more than 30,000 Americans a year, it's worth examining any tool that might help reverse that trend.